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Dental Assistant Esthetic Fixed Prosthesis

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by

Rachael Wiebe

on 2 May 2015

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Transcript of Dental Assistant Esthetic Fixed Prosthesis

THE BASICS
SUMMARY
and watch some videos to!
A review of fixed prosthesises and introduction to the esthetic side of fixed prosthesises
Fixed Prosthesis:
Esthetics

FIXED
PROSTHESIS

Things U should Know
What is a crown??
An indirect restoration made by a laboratory technician-typical outside of the dental office
Provisional restorations are necessary for protection the margins/ prevent shifting, restore basic function, and esthetics of the tooth
Review of the basics
Variations of Fixed Prosthesis
Full cast (covers the entire tooth)
Single unit
Bridge (multiple crowns casted together)
Full coverage
Maryland
¾ (covers ¾ of the tooth)
Veneer
Inlays
Onlays

All can be cast as all metal, PFM, or all porcelain
Review of the basics
What types of materials are used for provisional restorations.
Metal
Lined or unlined stainless steel (ss)
Lined or unlined aluminum
Polymer Shells
Polymer shell filled with composite resin material
Lined or unlined Polycarbonate
Custom Acrylic
Laboratory-fabricated coverage
Less common
Used in large cases
Review of the basics
Right: All porcelain

Middle: PFM with high-noble coping

Right: PFM with base-metal coping
Base metal
Gold
Types of crowns -All Metal

Base metal
High-Noble
Noble
Review of the basics
Types of crowns-PFM
Base metal coping with outer porcelain surface
High-Noble coping with outer porcelain surface
Noble coping with outer porcelain surface
Review of the basics
ESTHETIC
CERAMICS
FABRICATION
SHADE SELECTION
The dental assistant or hygienist may be asked to assist the dentist in choosing the appropriate shade for a restorative procedure.
An inappropriate shade selection will result in a mismatch to the patient’s dentition.
The characteristics of hue, chroma, and value must be taken into consideration when shade is determined.
Shade Taking
The lighting in which a shade is viewed is very important.
Most dental offices have a combination of fluorescent and incandescent lighting.
Natural light is often the preferred source, and some offices replace their light bulbs with natural light–mimicking bulbs.
Lighting for Shade Taking
A wide variety of tooth-colored esthetic materials are available to the dental team for use in restoring a patient’s dentition.
The dental team must work together when utilizing these materials.
An understanding of the properties involved will contribute to a successful outcome.
Summary
Use a neutral background.
Have patients remove lipstick and/or heavy makeup.
Cover colorful clothing.
Ideally, a neutral gray tone works best.
Matching the Shade
Esthetic Fixed Prosthesis
Single Unit
Full coverage
Porcelain Jacket
All Ceramic
Heat-Pressed
Sintered
PFM

¾
Onlays
Inlays
Bridges
Full coverage
Maryland
Veneers
Types: esthetic fixed
Ceramics : describes porcelain and other new materials that are similar in appearance to porcelain but vary in terms of
Composition
Mode of fabrication
Physical properties
What is a Ceramic?
Ceramics : describes porcelain and other new materials that are similar in appearance to porcelain but vary in terms of
Composition
Mode of fabrication
Physical properties
What is a Ceramic?
Porcelain : describes a class of tooth-colored dental materials.
Feldspathic porcelain is the technical term for porcelain used in dentistry
Supplied as powder in various shades
The technician selects shade, mixes powder with water to make a putty
Feldspathic porcelain must be fired to bond the porcelain crystals
What is Porcelain?
Feldspathic porcelain
1st esthetic material used for esthetic fixed prosthesis
Used in slip casting
More on Feldspathic porcelain
Highly esthetic.
The more glass add the more esthetically pleasing
Restorations using ceramics are only fabricated in a dental lab
Over the past three decades, ceramic materials have increased in strength and are widely use.
They are classified 3 groups based on their composition:
Mostly glass
Particle-filled glass
Polycrystalline
What to know about dental ceramics
Filler particles are added ceramic/glass material to:
Create variations of color
Make the material opaque (ceramic and ceramic/glass materials are not opaque by themselves
Polycrystalline = higher strength
Stronger ceramics may be used as the core (coping) of the restoration with more esthetic porcelains buildup on top to achieve a restoration that is:
Esthetic
Translucent
STRONG!
What to know about dental ceramics
Left: An all porcelain crown

Right: Zirconium coping which the porcelain was built up on top of.
What to know about dental ceramics
Slip Casting
W/Ceramic or metal coping
Directly onto the die
(for veneers or Porcelain Jackets)
Heat-Pressing
Computer Aided Design-Computer Aided Manufacturing
Options in fabrication
Small cracks
develop when the porcelain is put under occlusal loading.
They spread over time until the porcelain gives way.
Chemical bond between porcelain and the metal oxides.
Why would porcelain fail?
1st Just like all metal restorations, porcelain begins with a coping.
The coping can be create metal (base, noble, or high-noble) or a ceramic material, such as zirconium.
Fabrication using sintering as an example
2nd application of porcelain. The porcelain is selected according the the selected shade-beginning with the dentin porcelain and then the incisal/occlusal porcelain. Processes differ for PFM and all ceramic restorations because of the coping material
Porcelain is applied incrementally on top of the coping.
Created from a
Heat-Press
CAD-CAM
Metal Coping:
Ceramic Coping:
Fabrication using sintering as an example
PFM: Note the visible opaque porcelain.
Fabrication using sintering as an example
Fabrication using sintering as an example
3rd Firing
the restoration first vacuum fired under and then air fired.
Fabrication using sintering as an example
5th Glazing
The final contours are made and porcelain is glazed and fired.
Fabrication using sintering as an example
6th Delivery
The crown is delivered to the dental office and then the patient.

* Remember: It is 2-3 weeks from the time of the crown prep to the time of the crown seat appointment
Fabrication using sintering as an example
When porcelain restorations are delivered, they often must be adjusted to ensure fit.
These adjustments remove the glaze from the finish.
These restorations may be returned to the laboratory to be re-glazed or polished at chairside before cementing.
Fabrication using sintering as an example
Old method
Rarely or seldomly used
Uses a porous gypsum to pore/create die
Mixes porcelain into a mass or slip (less viscous than porcelain used for sintering)
Porcelain is pressed/stacked directly onto die.
Uses ceramics with:
Zirconium
(Brand names: Lava, Procera, In-Ceram, Cercon)
Spinel (magnesium)
Alumina
Slip casting
Uses the Lost wax technique
A block of ceramic, in the correct shade, is select
The investment is placed into the heat press machine with the set on top of the sprue-former area.
The ceramic is heated and pressed into the investment.
Heat-Pressing
Lost wax technique
Die is created
A wax pattern is created
The wax pattern is invested
The investment is heated to burn-out the wax
Review the basics
Lab
Office
CAD/CAM Used in office and lab settings
Used to create an all ceramic crown at chairside can take 45 to 3 hours.
45 mins for material which does not require firing
Up to 3 hours for material which requires firing (stronger)
Can create inlays, onlays, veneers, and full coverage crowns.
Used to create ceramic and metal copings which porcelain is stack onto.
Used to make all ceramic crowns without a coping.
All-Ceramic Crowns
The most commonly used restorations in fixed prosthodontics are combinations of porcelain and metal.
Low-fusing porcelain is used to bond to the metal.
When porcelain is applied to the metal and the two materials are heated together, the porcelain chemically fuses to the oxides on the metal, forming a durable bond.
Porcelain-to-Metal Restorations
All-ceramic crowns have a more life-like appearance than PFM crowns because they do not have an opaque layer to hide metal.
Light transfer is greater=More Natural Appearance
All-Ceramic
Crowns
More esthetically pleasing
They can be used for inlays, onlays, crowns, and veneers.
The major drawback of all-ceramic restorations is their potential to fracture.
All-Ceramic Crowns
The metal coping is fired to create
oxides. Then the opaque would be
heated to create oxides and an opaque
porcelain would be applied first to hide
the metal oxidation.
Sintering
4th Checking Contours/contacts/occlusion
The crown is placed back on the model and the contours, contact, and occlusion is checked. At the point the crown can be contoured with porcelain burs and contouring burs to remove bulk or to just add contour. Additional porcelain may be placed it necessary (re-firing would need to take place-this process maybe repeated 7-8 times due to 25-40% shrinkage).
Fabrication using sintering as an example
Full transcript